a tough nut to crack in a sentence

Examples

1. "Record companies have been a tough nut to crack, " said bass Barry Carl.
2. "It's a tough nut to crack as to what Haiti needs more of ."
3. That's one of the main reasons why this thing is such a tough nut to crack ."
4. With the Israelis and the Palestinians, well, that was always going to be a tough nut to crack.
5. But the local phone business is proving a tough nut to crack for even the largest and best financed cable companies.
6. That's a tough nut to crack for the likes of Red Bullet, Snuck In, and Hugh Hefner.
7. When Martin suggested then that TMS would be a tough nut to crack, turns out he was being politically correct.
8. Winning Laotian cooperation for the Vietnamese to visit the sites has been " a tough nut to crack,"
9. Pakistan enjoyed territorial supremacy throughout the match against Spain, but found Spanish goalkeeper Bernardino Herrera a tough nut to crack.
10. In the 20 years after their international debut in 1976, the Americans developed a cachet as tough nuts to crack.